Some snowmobile rear suspensions have been enhanced with adjustable features for adapting the rear suspension to individual needs of riders. Commonly, the snowmobile rear suspensions have adjustable shock absorbers which alter the compression and rebound damping of the shock absorbers of the snowmobile rear suspension. Additionally, snowmobile rear suspensions have adjustments which are linked to the amount of tension within the coil and torsion springs of the snowmobile rear suspension. Such adjustments are done manually by the user. By adjusting the load (or preload) of the (one or more) torsion springs, the user can change the suspension characteristics to meet his/her desired characteristics.
The torsion springs are used to expand the rear suspension after it has been compressed so that it is ready to absorb a subsequent impact. The torsion springs are disposed around a transverse rod of the rear suspension arm(s) of the rear suspension. The first end of each torsion spring is in contact with the slide rails and the second end is in contact with the rear suspension arm. The torsion springs apply a bias force to rotate the rear suspension arm with respect to the slide rails so as to raise the tunnel away from the ground. Sometimes, only one torsion spring is used.
In one system, the short end of the torsions springs, i.e. the second end in contact with the rear suspension arm, is received on a rotatable block. The block has one or more sides which are non-equally distanced from the rotation axis of the block, such that the preload of the torsion springs can be altered by rotating the block. The preload of the torsion springs is determined by the side of the block in contact with the second ends of the torsion springs. The rotation of the block is done manually using a tool such as a wrench, by applying a torque to the block so as to rotate it.
In order to rotate the block, the user may have to kneel on the ground and extend his/her arm under the tunnel into the rear suspension system when accessing the block. As can be easily understood, such position can be cumbersome to apply sufficient force to rotate the block. In some cases, the user can dirty his clothing if contact is made with some of the snowmobile rear suspension components while making the adjustment.
Therefore, there is a need for a mechanism to adjust the load (or preload) on a torsion spring of a rear suspension assembly that is easily accessible to for the user.